ch 22 Flashcards
conduction - Send A Big Bounding Pulse
- SA node
- AV Node
- Bundle of His
- R/L Bundle Branches (right and left)
- Purkinje Fibers
depolarization: - to + contraction
Re-polarization + to - relaxation
cardiac conduction system generates and transmits electrical impulses which stimulates contraction of the atria and then the ventricles
SA Node (SinoAtrial node)
“automaticity”
primary pace maker of the heart
creates electrical impulse of 60-100 BPM (normal heart rate)
AV Node (AtrioVentricular)
secondary pacemaker of the heart (backup pacemaker)
if SA node malfunctions, the AV node takes over
40-60 BPM
purkinje fibers
if SA and AV nodes fail the purkinje fibers can fire at a rate of 30-40 BPM
P Wave
reflects conduction of an electrical impulse through the atrium
represent atrial depolarization
QRS Complex
reflects conduction of an electrical impulse through the ventricles
represent the ventricles depolarization
T Wave
reflects repolarization of the ventricles
PR Segment
flat line between the end of P-wave and the start of QRS Complex
reflects the delay between atrial and ventricular activation
ST Segment
reflects the end of QRS Complex to the beginning of the T wave
PR Interval
reflects the conduction of an electrical impulse from the sinoatrial node (SA) through the atrioventricular node (AV)
QT interval
reflects the time from ventricular depolarization through repolarization
measured from beginning of QRS complex to the end of the T wave
RR Interval
the duration between the beginning of one QRS complex and the beginning of the next QRS complex
used to calculate ventricular rate and rhythm
PP Interval
the duration between the beginning of one P wave and the beginning of the next P wave
used to calculate atrial rate and rhythm
U Wave
reflect the purkinje fibers repolarization
not seen unless patient is hypokalemic (low Potassium)
Basic rhythms
normal sinus: 60-100 bpm
sinus tachycardia: > 100 bpm
sinus bradycardia: < 60 bpm
ekg interpretation: P wave
should be present and upright
comes before QRS complex
one P-wave for every QRS Complex
EKG interpretation: PR Interval
measure PR interval
normal: 0.12 - 0.2 seconds
EKG Interpretation: QRS Complex
is every P wave followed by a QRS complex?
should not be widened or shortened - may indicate problems
widened is often seen in PVCs, electrolyte imbalances, and drug toxicity
normal: 0.06 - 0.12 seconds
EKG Interpretation: RR interval
are the RR intervals consistent?
regular or irregular
ekg boxes
1 large box = 0.20 seconds
5 large boxes = 1 second
1 small box: 0.04 seconds
normal sinus rhythm
rate: 60-100 bpm
P waves: present, consistent configuration, one p wave before each QRS complex
PR interval: 0.12 - 0.20 seconds and constant
QRS duration: 0.06 - 0.12 seconds and constant
EKG interpretation: determine heart rate 6 SECOND METHOD
count the number of Rs in between the 6 second strips and multiply by 10 ( be sure to check that the strip is 6 seconds by counting the boxes)
6 Rs X 10 = 60 beets per minute
EKG interpretation: determine heart rate BIG BOX METHOD
300 divided by teh number of big boxes between 2 Rs
300/5 = 60 Bpm
electrocardiography
12 - lead ECG
continuous monitoring
hardwire
A cardiac monitor at the patient’s bedside for continuous reading; this kind of monitoring, usually called hardwire monitoring, is used in intensive care units
Telemetry
A small box that the patient carries and that continuously transmits the ECG information by radio waves to a central monitor located elsewhere
ambulatory monitoring
A small, lightweight tape recorder–like machine (called continuous ECG monitoring, which might include a Holter monitor or a patch monitor) that the patient wears for a prescribed period and that continuously records the ECG, which is later viewed and analyzed with a scanner
intermittent monitoring using a looped recorder
A very small device inserted under the skin or worn externally on a wrist band that can perform ECG monitoring on demand whenever a patient is symptomatic
EKG indications for dysrhythmias
sinus bradycardia/tachycardia
AV blocks
atrial fibrillation
ventricular asystole
premature atrial complexes (PACs) and premature ventricular complexes (PVCs)
supraventricular tachycardia
ventricular tachycardia
ventricular fibrillation
client presentation for dysrhythmias
cardiovascular disease
myocardial infarction (MI)
hypoxia
acid-base imbalances
electrolyte disturbances
Preprocedure nursing actions cardio
- prepare client for 12-lead ECG if prescribed
- position client in supine with chest exposed
- wash client’s skin to remove oils
- if the area on which electrode is placed has hair CLIP DO NOT SHAVE area to provide skin adherence and electrical conduction
- attach one electrode to each of the client’s extremities by applying electrodes to flat surfaces above the wrists and ankles and the other six electrodes to the chest, avoiding chest hair
intraprocedure nursing actions cardio
monitor for manifestation of dysrhythmias (chest pain, decreased LOC, shortness of breath, hypoxia)
client education: remain still and breathe normally while the 12-lead ECG is performed
post-procedure nursing actions cardio
- remove leads from the client
- print ECG report
- notify provider
- apply a holter monitor if the client is on a telemetry unit and/or needs continuous cardiac monitoring
- continue to monitor the client for dysrhythmia
sinus node arrhythmias
originate in the SA node
-sinus bradycardia
-sinus tachycardia
-sinus arrhythmia
atrial arrhythmias
-atrial flutter
-atrial fibrillation
-supraventricular tachycardia
-premature atrial complex
ventricular arrhythmias
-premature ventricular complex
-ventricular tachycardia
-ventricular fibrillation
-ventricular asystole
conduction abnormalities
-first degree atrioventricular block
-second degree atrioventricular block, type 1 (Wenckeback)
-Second-Degree Atrioventricular Block, Type 2
-third-Degree Atrioventricular Block
sinus bradycardia - CAUSES
-can be normal for some people (athletes who have baseline bradycardic rate)
-damage to the heart d/t heart disease
-vagal stimulation
-hypothermia, hypoglycemia
-hypothyroidism
-certain drugs or medications (cholinergics, adrenergic blockers, opioids)
sinus bradycardia - SIGNS AND SYMPTOMS
-slow pulse rate
-near fainting or fainting (syncope)
-fatigue, dizziness, lightheadedness
-shortness of breath
-chest pain
-confusion or trouble with memory
-easily tired during physical activity
sinus tachycardia - CAUSES
-exercise
-hypertension
-emotional distress, anxiety, fear
-damage to the heart d/t heart disease
-electrolyte imbalance
-hyperthyroidism
-severe bleeding/shock/hypovolemia (low blood plasma level)
-certain stimulants or medications (anticholinergics/adrenergics, caffeine, nicotine)
sinus tachycardia - SIGNS AND SYMPTOMS
-rapid pulse rate
-sensation of rapid heartbeat (palpitations)
-shortness of breath
-dizziness, fainting (syncope), anxiety
-chest pain
-trouble exercising
-headaches
treatment - arrhythmias
-maintain airway, supplemental oxygen, obtain IV access, monitor EKG
-in unstable patient will have altered LOC, ischemia (reduced blood flow), shock, decreased BP
-synchronized cardioversion
-if QRS wide: >0.12 sec
-carotid massage (vagal stimulation)
antiarrhythmic medications
-adenosine
-amiodarone
-Beta blocker (-olol)
-procainamide
premature atrial contractions
early extra beats that originate in the atria (upper chambers of the heart). PAC are harmless and do not require treatment
atrial fibrillation
very common irregular hearth rhythm that causes the atria to contract abnormally
supraventricular tachycardia
common dysrhythmia that occurs when an impulse is conducted to an area in the AV node that causes the impulse to be rerouted back into the same area over and over again at a very fast rate. each time the impulse is conducted through this area, it is also conducted down into the ventricles, causing a fast ventricular rate
atrial flutter
similar to atrial fibrillation but has a more regular pattern
